The present invention relates to a method and an apparatus for manufacturing an AC generator""s stator for a vehicle such as a passenger car or a truck.
Since the AC generator for a vehicle has been required to be more powerful, the resistance of the stator winding is required to be lower and lower, thereby reducing the length of the magnet wire.
It is well known that a plurality of U-shaped conductor segments are respectively inserted into slots of a stator core in the same direction and are connected with each other to form a stator winding, thereby increasing the output power of a vehicular AC generator, as disclosed in International Publication Number WO 92/06527 (1992). Because U-shaped conductor-segments can be disposed very regularly in this structure, the slot-space factor and the output power thereof can be increased.
Before turn portions of conductor segments are twisted in a manufacturing process of the above conventional structure, an annular holder 310 holds the turn portions 301a, 302a, 303a of the conductor segments 301, 302, 303 as shown in FIG. 16 of the present application. Straight portions 301b, 302b, 303b are inserted into twisting tools 311, 312, which are twisted relative to the annular holder 310 in directions opposite from each other by an angle of T/2 (T is a pole-pitch angle). As a result, the straight portions 301b, 302b, 303b of the segments 301, 302, 303 are twisted at T/2 as shown in FIG. 17.
Because the annular holder 310 holds entire arc portions of the turn portions 301a, 302a, 303a of the segments 301, 302, 303, the coil ends becomes longer than coil ends formed without using the annular holder 310. That is, the wire length becomes longer.
In this conventional method, when the segments 301, 302, 303 are inserted into the slots, the segments 301, 302, 303 are held by the annular holder 310 at the turn portions 301a, 302a, 303a. The straight portions 301b, 302b, 303b are inserted into the slots with only the turn portions 301a, 302a, 303a being held.
In this method, the segments 301, 302, 303 are held only at the turn-portions 301a, 302a, 303a disposed on the end of the stator core opposite the end from which the segments are inserted into the slots. Therefore, the straight portions 301b, 302b, 303b can not be positioned accurately, and the segments 301, 302303 may collide with the slot-inner-walls to be damaged when the conductor segments are inserted into the slots. If the number of slots increases, the distance between the slots decreases, and higher accuracy is necessary to the method. However, it is difficult for this method not provide such high accuracy.
The present invention is made to solve the above problems and to provide a method and an apparatus for manufacturing a stator that improves the accuracy in inserting the segments into the slots.
The present invention is to provide a method and an apparatus for manufacturing a stator that reduces damages to the segments, and which form the short coil ends.
The present invention is also to provide a method and an apparatus for manufacturing a stator that has short coil ends.
To achieve the above objects, there is a feature characterized by including a conductor holder (21, 22) holding conductor segments (3, 31, 32) and an axial-moving mechanism (214) which moves the conductor holder (21, 22) in the axial direction relative to a stator core (1). The conductor holder includes a guide guiding straight portions (31b, 31c, 32b, 32c) of the conductor segments (3, 31, 32) inserted into the slots (2) in an axial direction.
Because the guide guides the straight portions of the conductor segments (3, 31, 32) inserted into the slots (2), the positioning-accuracy can be improved compared with a method in which only one end of the turn-portion is held. As a result, the conductor segments ( 3, 31, 32) are prevented from being damaged by their collision with the slot-inner-walls. The guide of the conductor holder (21, 22) is a member guiding straight portions (31b, 31c, 32b, 32c) of the conductor segments (3, 31, 32) into the prescribed positions. The guide can be integrated into a conductor holder which holds and moves the straight portions (31b, 31c, 32b, 32c) of the conductor segments ( 3, 31, 32), or into a guide member which guides the conductor segments ( 3, 31, 32) in a inserting step.
It is preferable, to improve positioning-accuracy, that the conductor holder (21, 22) guides the straight portions (31b, 31c, 32b, 32c) at portions adjacent to an end of the stator core (1)
The conductor holder (21, 22) includes a circumferential guide (211d, 211e) which guides opposite sides of the straight portions (31b, 31c, 32b, 32c) in the circumferential direction of the stator core (1).
Because the circumferential guide restricts the circumferential movement of the conductor segments (3, 31, 32), the conductor segments (3, 31, 32) are prevented from colliding with inner-walls of the slots (2).
The conductor holder (21, 22) comprises a radial guide (211c, 221) which guides opposite sides of the straight portions (31b, 31c, 32b ; 32c) in the radial direction of the stator core (1).
Because the guide restricts radial movement of the conductor segments (3, 31, 32), the conductor segments (3, 31, 32) can be prevented from colliding with the radially inner-walls of the slots (2).
The circumferential guide (211d, 211e) and radial guides (211c, 221) move in the radial direction of the stator core (1).
The conductor holder (21, 22) holds the plural conductor segments (3, 31, 32) at the same time.
The circumferential-directional guide portions (211d, 211e) and the radial-directional guide portions (211a, 221c) can be moved in the radial direction.
Because a plurality of conductor segments (3, 31, 32) are held and inserted simultaneously, manufacturing efficiency can be improved.
A presser (16) can be added to press-fits the conductor segments (3, 31, 32) into the stator core (1) in the axial direction of the stator core (1).
Therefore, the conductor segments (3, 31, 32) can be inserted into the slots and position the same as desired.
The conductor segments (3, 31, 32) are preferably U-shaped, and the presser (16) comprises a circumferential supporting portions (16a) restricting turn portions (31a, 32a) of the conductor segments (3, 31, 32) to move in the circumferential direction of the stator core (1).
In this structure, because the circumferential supporting portions (16a) sandwiches the turn portions (31a, 32a) at the middle between opposite circumferential sides, the circumferential movement of conductor segments (3, 31, 32) can be restricted. The circumferential supporting portions (16a) prevents the circumferential movement of the conductor segments (3, 31, 32) so that the conductor segments (3, 31,32) can be prevented from colliding with the circumferential inner-walls of the slots (2) when the same are inserted into the slots (2).
The circumferential holder (16a) has a projection disposed on a surface of the presser (16) in contact with the turn portions (31a, 32a) of the conductor segments (3, 31, 32).
An axial holder (24) is further included at an end of the stator core opposite the presser (16) to hold edge portions (31d, 31e, 32d, 32e) of the conductor segments (3, 31, 32) in an axial direction when the presser (16) presses down the conductor segments (3, 31, 32).
When the presser ( 16, 23) presses down the conductor segments (3, 31, 32), both the turn portions ( 31a, 31b) and the edge portions (31d, 31e, 32d, 32e) are restricted. Therefore, the conductor segments (3, 31, 32) can be inserted into the slots (2) evenly with both the inner and outer segments thereof. Therefore, the straight portions (31b, 31c, 32b, 32c) of the conductor segments (3, 31, 32) can be prevented from being damaged in the slots (2).
The apparatus for achieving the above object includes a first turning tool (11) which holds one straight portions (31b, 32b) of the U-shaped conductor-segments (3, 31, 32), a second turning tool (12) which holds the other straight portions (31c, 32c) of the U-shaped conductor-segments (3, 31, 32) and turns relative to the first turning-tool (11), and a circumferential holder (16a) which holds middle portion of the turn portions (31a, 32a) of the U-shaped conductor segments (3, 31, 32) and restrict circumferential movement of the turn portions (31a, 32a).
When the turn portions (31a, 32a) are twisted, the circumferential supporting portion (16a) holds only the radially middle portions of the turn portions (31a, 32a) only in the circumferential direction. When the straight portion (31b, 31c, 32b, 32c) of the U-shaped conductor segments (3, 31, 32) are widened in the circumferential direction, only the middle portions of the turn portions (31a, 32a) are fixed so that the both sides of the turn portions can be bent smoothly in the curved line.
The U-shaped conductor-segments (3, 31, 32) include overlapping conductor segments of different radiuses of curvature. The first turning tool (11) and the second turning tool (12) respectively hold straight portions (31b, 32b) extending from opposite sides of the turn portions (31a, 32a) of the overlapping conductor segments (3, 31, 32) having the different radiuses. The circumferential holder (16a) restricts circumferential movement of the overlapping turn-portions (31a, 32a).
Thus, the overlapping turn portions (31a, 32a) can be twisted simultaneously.
Holding holes (111, 112, 121, 122) are provided in the first turning-tool (11) and the second turning-tool (12) in the axial direction thereof to hold the straight portions (31b, 31c, 32b, 32c) of the conductor segments (3, 31, 32).
As many the holding holes (111, 112, 121, 122) as a number corresponding to the number of the slots (2) can be provided at equal intervals in the circumferential direction.
A method to achieve the above object includes a fixing step of inserting straight portions (31b, 31c, 32b, 32c) of U-shaped conductor-segments (3, 31, 32) into holding holes (111, 112, 121, 122) of a first turning-tool (11) and of a second turning-tool (12), a turn-portion-holding step of holding only a middle portion of the turn portions (31a, 32a) to restrict circumferential movement of the first and second turning-tools (11, 12), and a twisting step of twisting the first turning-tool (11) and the second turning-tool (12) relative to each other.
When the turn portions (31a, 32a) are twisted, the circumferential holder (16a) holds the turn portions (31a, 32a) only circumferentially and only at the radially middle portion of the turn portions (31a, 32a)
When the straight portions (31b, 31c, 32b, 32c) of the U-shaped conductor segments (3, 31, 32) are widened circumferentially, only the middle portion of the turn portions (31a, 32a) is fixed so that the opposite sides of the turn portions (31a, 32a) can form a smooth curve.
The plural conductor segments (3, 31, 32) can be aligned in the circumferential direction. Plural turn portions (31a, 32a) having different radius of curvature can be overlapped.
Thus, the turn portions (31a, 32a) of the plural conductor segments (3, 31, 32) can be twisted simultaneously.
The method of achieving the above object includes a holding step of holding U-shaped conductor segments (3, 31, 32), an inserting step of guiding and inserting straight portions (31b, 31c, 32b, 32c) from edge portions (31d, 31e, 32d, 32e) thereof into slots (2), and a press-fitting step of press-fitting the U-shaped-conductor segments (3, 31, 32) into the slots (2) at turn portions (31a, 32a) thereof.
Because the conductor segments are guided into the slots at portions adjacent to the slots, higher positioning-accuracy can be obtained as compared with turn portions supported only at the turn portions (31a, 32a). As a result, the conductor segments can be prevented from colliding with the inner-walls of slots, thereby preventing damages.
The inserting step restricts movement of the turn portions (31a, 32a) of the U-shaped conductor segments (3, 31, 32) in the circumferential directions of the stator core (1).
The press-fitting step includes a step of restricting movement of the turn portions (31a, 32a) at the middle thereof.
Therefore, the conductor segments (3, 31, 32) can be prevented from shifting in the circumferential direction when the same are inserted in to the slots (2) so that the same can be prevented from colliding with the inner walls of the slots (2).